Apparatus for administering parenteral liquids



Jan. 17, 1957 i R. I. BERGMAN APPARATUS FOR ADMINISTERING PARENTERAL LIQUIDS Filed Jan 10, 1964 INVENTOR. F/ (7/4/75 I. Bafli/W/i/V Jan. 1 7,-1967 BERGMAN APPARATUS FOR ADMINISTERING PARENTERAL LIQUIDS Filed Jan 10, 1964 ifi'dfA fyf United States Patent 3,298,367 APPARATUS FOR ADMINISTERING PARENTERAL LIQUIDS Richard I. Bergman, 165 Valley Road, Princeton, NJ. 08540 Filed Jan. 10, 1964, Ser. No. 336,949 2 Claims. (Cl. 128-414) The present invention relates to an apparatus for administering parenteral liquids, and more particularly to such a device incorporating a capillary flow controller which facilitates the setting .of substantially exact and unchanging flow rates during the administration of such liquids.

The administration of parenteral liquids, e.g., by intravenous infusion of blood, plasma, dextrose solutions or the like, is a common hospital procedure. Such infusions are customarily carried out employing 1V kits incorporating .a bottle or other container of liquid suspended above the patient and having a drop counting chamber facilitating the determination of the drip rate therethrough, a drip tube through which the liquid to be infused flows by gravity feed, and an administering needle connected to the drip tube. The infusion rate is varied by use of a pinch valve associated with the drip tube. When such infusions are carried out the drip tube and needle are initially purged of air, the needle inserted in a vein, the pinch valve turned to compress the drip tube and thereby restrict the initial flow, and the number of drops falling through the drop counting chamber determined and varied as desired by trial and error adjustment of the pinch valve.

The preceding operations require the full time attention of the physician or other attending personnel for several minutes. Moreover, in addition to being time consuming, the preceding method of flow control is manifestly inaccurate. In fact, after the desired flow is finally obtained by trial and error operations, it may frequently change by as much as 100% within the next few minutes, necessitating readjustment. Undesired increases in the rates of administration of parenteral liquids have, in extreme cases, resulted in patients deaths. Obviously, large flow decreases are similarly undesirable.

Over long periods of time infusion rates utilizing such commercial IV kits decrease by 100%, unless the pinch valve employed to set the initial flow rate is readjusted. This is the case since, the pinch valve is customarily placed directly under the bottle for convenience in operation, and as the liquid level in the infusion bottle falls, the hydrostatic head providing the driving force for flow through the constriction at the pinch valve decreases. In a limiting case, flow will cease when the bottle is empty and decrease proportionately as the bottle empties unless the pinch valve is readjusted.

Over short periods of time the liquid flow rates may also vary by as much as 100% of the initial rate. Hence, when the administering needle is inserted so that the opening in its end is partially obstructed by the wall of the patients vein, a sudden increase in flow may result when the patient moves so that the end of the needle is no longer blocked. Similarly, decreased flow rates may result from the inherent characteristic of the pinched plastic drip tube to flow with time, thereby changing the cross-sectional area thereof and resulting in an inevitable change in the flow rate therethrough.

Accurate control of the rate of administration of parenteral liquids is particularly important in certain instances, e.g., in the administration of oxytocin during childbirth or the infusion of various liquids into pediatric patients, during which drip rates as low as from 0.05 to 0.5 ml./ min. (1 to 8 drops/min, each drop approximating from about 0.05 to 0.06 ml.) may be required. Controlling infusion rates to such a degree of accuracy by the pinch valve procedure described hereinabove is extremely difficult, even with constant attention on the part of the attending personnel.

It is accordingly among the objects of the present invention to provide an apparatus for administering parenteral liquids, incorporating a capillary flow device which effects the setting of substantially exact and unchanging flow rates of the liquids to be administered.

A further object of the invention is to provide such a flow controller which is simple and economical to manufacture and which may be provided as a component of a disposable IV kit, or as a separate disposable unit which may be used with existing devices.

Other objects and advantages of the present invention will be apparent from a consideration of the following detailed description thereof, taken in consideration with the accompanying drawing in which:

FIGURE 1 is a perspective view of an apparatus for administering parenteral liquids incorporating one embodiment of the capillary flow controller hereof; and

FIGURE 2 is a partially schematic, enlarged cross-section of the flow controller incorporated in the device shown in FIGURE 1.

In accordance with the invention a capillary flow controller is provided for use in an apparatus for administering parenteral liquids comprising a bottle containing the liquid to be administered, a drip tube connected thereto and an administering needle through which the liquid flows by gravity feed. The flow controller, which is connected to the drip tube sufficiently downstream of the supply bottle to provide a substantial hydrostatic head of the liquid above the controller, comprises at least one capillary tube having a predetermined internal cross section suflicient to establish a substantially exact and unchanging drip rate therethrough, and a valve element for initiating or terminating the liquid flow through such capillary. A device such as a drip chamber or rotameter may optionally be used to indicate drip rate.

When precise flow control is not important and it is solely necessary to limit the maximum flow through the IV kit, a single capillary tube may be employed. The resulting controller may incorporate an on-off valve element or, alternatively, may be used in conjunction with an existing IV kit having a pinch valve used to adjust flow rate, the capillary tube limiting the upper flow rate with the on-olf or pinch valve open. When, for example, the controller is incorporated in an IV kit used for the administration of plasma to an adult cardiac patient, a capillary permitting passage of a maximum of about 50-60 drops/ min. (about 3 ml./ min.) may be employed.

Preferably, however, the flow controller incorporates a first header element connected to the drip tube, a second header element connected to the administering needle, a plurality of capillary tubes connected in parallel between the headers, having the same or different internal cross-sections, and on-off valve elements associated with the several capillaries, such elements effecting the setting of varying, substantially exact and unchanging flow rates through one or more of the capillary tubes to the administering needle of the IV kit.

One preferred embodiment of the invention is illustrated in FIGURE 1. The IV kit shown comprises a ortable supporting structure mounted upon Wheels or casters 11 and including a base plate 12 upon which a post 13 is mounted carrying a ring 14 at its upper end. A supply bottle 15, in which plasma, dextrose solution or a like parenteral liquid is contained, is hung by a handle 16 from a hook 17 secured to the ring. The bottle 15 includes a separate or integral drop counting chamber 18 connected by a flexible tube 19, which may be constituted of polyethylene or other elastomeric material, to an administering needle 21.

In accordance with the present invention a capillary flow controller, indicated generally at 22, is connected into the drip tube lfi spaced from the supply bottle 15. By connecting the flow controller downstream of, and spaced from the supply bottle 15 a relatively large hydrostatic head, e.g., about 3 feet, is provided above the flow controller. As the bottle 15 is emptied the percentage change in such hydrostatic head is relatively small, thereby minimizing the change in infusion rate during extended use. Moreover, such arrangement minimizes the change in the drip rate when the patient thrashes and momentarily raises venous pressure, since the resulting change in back pressure is small compared to the total hydrostatic head.

The capillary flow controller 22 includes a first header element 23 connected to the drip tube 10 and a second header element 24 connected to the portion of the drip tube 19 adjacent the administering needle 21. Secured in parallel to the header 24 are four capillary tubes 25, 26, 27 and 28 which are attached, in turn, to the header 23 by short lengths 29 of flexible plastic tubing. An onoif valve element 31 is secured to each length of tubing 29 for effecting initiation or termination of fluid flow through the corresponding capillary tube connected thereto. Any of the many commercially available relatively simply designed on-oif valve elements may be so utilized. Alternatively, tubing 29 and valves 31 may be rigid members, formed integrally with the capillary tubes 25, 26, 27 and 28 by techniques such as molding or casting.

The capillary tubes 25, 26, 27 and 28 may be made of stainless steel (e.g., similar to syringe needle tubing), glass, or plastic and may, if desired, be color coded for identification. As illustrated, they are provided of varying internal cross sections and lengths, in order to facilitate setting different incremental drip rates therethrough. Generally, the individual capillary tubes possess internal diameters of from about 0.002 to 0.085 inch and vary from about A to inches in length.

The several capillary tubes are advantageously secured in a unitary assembly supported, for example, within a plastic mounting block 32. The compact assembly of the header elements, capillary tubes and valve elements may be no more than about 2" X 1" x /z in overall dimensions.

In one embodiment the capillary tube 25 may possess an internal diameter of 0.008 inch and a length of 2 inches, tubes 26 and 27 may each have an internal diameter of 0.005 inch and a length of /2 inch, and tube 28, an internal diameter of 0.008 inch and a length of 1 inch. When tube 25 is provided with such dimensions, it passes about 8 drops/min. of parenteral liquids possessing flow properties not substantially different from water, tubes 26 and 27 each pass about 4 drops/min, and tube 28 about 16 drops/min.

Employing such a flow controller it is possible to control the infusion rates of liquids possessing flow characteristics not substantially different from Water in increments of 4 drops/min. over the range of from 4 to 32 drops/ min. This is a typical flow rate range for the infusion of oxytocin in dextrose solution, for example.

It will of course be understood that any number of capillary tubes having any desired dimensions may be utilized in the capillary fiow controller of the present invention, depending upon the desired drip rate range and incremental rate adjustments desired for the particular application in question.

The improved flow rate characteristics obtained by use of the capillary flow controller of the present invention in IV kits of the types which are commercially available are illustrated in the following examples.

Example 1 In vitro experiments were carried out with a commercial IV kit by placing the needle thereof through a rubber septum intoa 150 mm. high glass tube filled with a 5% dextrose solution. A constant discharge pressure of 150 mm. of liquid (approximating venous pressure) was thus maintained. A capillary flow controller was connected between the drip tube and the needle of the IV kit, the flow controller comprising a pair of capillary tubes connected in parallel, the first of which had an internal diameter of .005 and a length of and the second of which had an internal diameter of .005" and a length of Portions of the 5% dextrose solution (in water) were fed through the IV kit, employing an initial rate of 5 drops per minute. The change in the drip rate with time was determined and is indicated below:

Time (min) When one of the capillary tubes was eliminated a constant drip rate of 3 drops per minute was established by the remaining capillary.

Example 2 Example 3 Example 1 was repeated, employing a flow controller incorporating four capillary tubes connected in parallel, the tubes having lengths of 2", 1", W and and internal diameters of .008, .008, and .005", .005", respectively. The change in the drip rate with time was:

Time (min.) Rate (drops/ min.)

Other parenteral fluids with properties not substantially different from water, such as aqueous solutions of inorganic and organic salts and pitocin in dextrose solution, were tested with similar results. Dextran, a plasma extender flowed at about /3 the rate, substantially constant with time.

For comparison, similar in vitro experiments were performed with the IV kit employed in the preceding examples without, however, incorporating a capillary flow controller therein. The initial flow rates were set at 24 and 70 drops per minute using the pinch valve and the variations with time (without further manual adjustments) determined. The changes in drip rate with time were:

Time (min): Rate (drops/min.)

From the above it will be seen that the apparatus foradministering parenteral liquids incorporating a capillary flow controller, in accordance with the present invention, provides a means for establishing substantially exact and unchanging liquid flow rates as compared with previously known commercially available IV infusion kits.

Since various changes can be made in the embodiments described above without departing from the scope of the present invention, it will be understood that the preceding description is intended as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In an apparatus for administering parenteral liquids including a container holding the liquid to be administered, a drip tube communicating with said container through which said liquid flows by gravity feed, and an administering needle connected to said drip tube; the improvement comprising a capillary flow controller for regulating the flow of the liquid through said needle, the flow controller being connected to said drip tube sufficiently downstream from said container to provide a substantial hydrostatic head above the controller and comprising a first header connected to said drip tube; a second header connected to said needle; a plurality of capillary tubes connected in parallel between said first and second headers, each of said capillary tubes having predetermined lengths and uniform internal cross-sections throughout their lengths suflicient to provide varying incremental flow rates of said liquid through the flow controller when operated individually or simultaneously, and on-off valve means for each said capillary tube facilitating the flow of the liquid through one or more of said capillary tubes simultaneously.

2. The apparatus for administering parenteral liquids as defined in claim 1, in which each of said capillary tubes has an internal diameter of from 0.002 to 0.085 inch and a length of from A to 5 inches.

References Cited by the Examiner UNITED STATES PATENTS 2,229,903 1/1941 Schmohl et al. 137-599 2,771,878 11/1956 Folland et al. 128214 3,060,956 10/1962 Menzie 137-604 X RICHARD A. GAUDET, Primary Examiner.

DALTON L. TRULUCK, Examiner. 

1. IN AN APPARATUS FOR ADMINISTERING PARENTERAL LIQUIDS INCLUDING A CONTAINER HOLDING THE LIQUID TO BE ADMINISTERED, A DRIP TUBE COMMUNICATING WITH SAID CONTAINER THROUGH WHICH SAID LIQUID FLOWS BY GRAVITY FEED, AND AN ADMINISTERING NEEDLE CONNECTED TO SAID DRIP TUBE; THE IMPROVEMENT COMPRISING A CAPILLARY FLOW CONTROLLER FOR REGULATING THE FLOW OF THE LIQUID THROUGH SAID NEEDLE, THE FLOW CONTROLLER BEING CONNECTED TO SAID DRIP TUBE SUFFICIENTLY DOWNSTREAM FROM SAID CONTAINER TO PROVIDE A SUBSTANTIAL HYDROSTATIC HEAD ABOVE THE CONTROLLER AND COMPRISING A FIRST HEADER CONNECTED TO SAID DRIP TUBE; A SECOND HEADER CONNECTED TO SAID NEEDLE; A PLURALITY OF CAPILLARY TUBES CONNECTED IN PARALLEL BETWEEN SAID FIRST AND SECOND HEADERS, EACH OF SAID CAPILLARY TUBES HAVING PREDETERMINED LENGTHS AND UNIFORM INTERNAL CROSS-SECTIONS THROUGHOUT THEIR LENGTHS SUFFICIENT TO PROVIDE VARYING INCREMENTAL FLOW RATES OF SAID LIQUID THROUGH THE FLOW CONTROLLER WHEN OPERATED INDIVIDUALLY OR SIMULTANEOUSLY, AND ON-OFF VALVE MEANS FOR EACH SAID CAPILLARY TUBE FACILITATING THE FLOW OF THE LIQUID THROUGH ONE OR MORE OF SAID CAPILLARY TUBES SIMULTANEOUSLY. 